1. Technical Field
This document relates to methods and materials for quantifying ocular counter roll (OCR) and detecting vestibular otolith damage. For example, this document relates to devices for quantifying OCR, methods of making devices for quantifying OCR, and methods for using a device to quantify (e.g., quantify indirectly) OCR.
2. Background Information
The otolith organs (the utricle and saccule) of the inner ear vestibular system are the primary gravity sensors of the body. Activation of the otolith organs by linear acceleration generates spinal and ocular reflexes that act to maintain posture and gaze. OCR is an example of an otolith-ocular reflex in response to otolith activation. When the head is tilted to the side (ear moved toward the shoulder), the eyes roll in the opposite direction. This head tilt induced OCR is an orienting reflex that tends to align the eyes with the horizon. Damage to the otolith organs or their central connections can impair body and ocular stabilization. This can cause complaints of dizziness or imbalance that are difficult to diagnose without sophisticated and expensive measurement equipment. As a consequence, the cause of these disorders is often missed.